A Composite Nanosystem as a Potential Tool for the Local Treatment of Glioblastoma: Chitosan-Coated Solid Lipid Nanoparticles Embedded in Electrospun Nanofibers.

Glioblastoma multiforme (GBM) is one of the most prevalent and aggressive brain tumors for which there is currently no cure. A novel composite nanosystem (CN), consisting of chitosan-coated Solid Lipid Nanoparticles (c-SLN) embedded in O-carboxymethyl chitosan (O-CMCS)-containing nanofibers (NFs), was proposed as a potential tool for the local delivery of lipophilic anti-proliferative drugs. Coacervation was selected as a solvent-free method for the preparation of stearic acid (SA) and behenic acid (BA)-based SLN (SA-SLN and BA-SLN respectively). BA-SLN, containing 0.75% w/w BA sodium salt and 3% w/w poly(vinyl alcohol) (PVA), were selected for the prosecution of the work since they are characterized by the lowest size functional to their subsequent coating and incorporation in nanofibers. BA-SLN were coated with chitosan (CS) by means of a two-step coating method based on the physical absorption of positively charged CS chains on the SLN negative surface. Nile Red (NR), chosen as the hydrophobic model dye, was dissolved in a micellar solution of BA sodium salt and then added with a coacervating solution until pH ≅ 2.5 was reached. Immunocytochemistry analyses highlighted that CS-coated BA-SLN (c-BA-SLN) exhibited a higher accumulation in human glioblastoma cells (U-373) after 6 h than CS-free BA-SLN. Finally, the c-BA-SLN dispersion was blended with a solution consisting of freely soluble polymers (O-CMCS, poly(ethylene oxide) and poloxamer) and then electrospun to obtain NFs with a mean diameter equal to 850 nm. After the NFs dissolution in an aqueous media, c-BA-SLN maintained their physicochemical properties and zeta potential.

Recent Advances in the Development of In Situ Gelling Drug Delivery Systems for Non-Parenteral Administration Routes.

In situ gelling drug delivery systems have gained enormous attention over the last decade. They are in a sol-state before administration, and they are capable of forming gels in response to different endogenous stimuli, such as temperature increase, pH change and the presence of ions. Such systems can be administered through different routes, to achieve local or systemic drug delivery and can also be successfully used as vehicles for drug-loaded nano- and microparticles. Natural, synthetic and/or semi-synthetic polymers with in situ gelling behavior can be used alone, or in combination, for the preparation of such systems; the association with mucoadhesive polymers is highly desirable in order to further prolong the residence time at the site of action/absorption. In situ gelling systems include also solid polymeric formulations, generally obtained by freeze-drying, which, after contact with biological fluids, undergo a fast hydration with the formation of a gel able to release the drug loaded in a controlled manner. This review provides an overview of the in situ gelling drug delivery systems developed in the last 10 years for non-parenteral administration routes, such as ocular, nasal, buccal, gastrointestinal, vaginal and intravesical ones, with a special focus on formulation composition, polymer gelation mechanism and in vitro release studies.

Mucoadhesive and thermogelling systems for vaginal drug delivery.

This review focuses on two formulation approaches, mucoadhesion and thermogelling, intended for prolonging residence time on vaginal mucosa of medical devices or drug delivery systems, thus improving their efficacy. The review, after a brief description of the vaginal environment and, in particular, of the vaginal secretions that strongly affect in vivo performance of vaginal formulations, deals with the above delivery systems. As for mucoadhesive systems, conventional formulations (gels, tablets, suppositories and emulsions) and novel drug delivery systems (micro-, nano-particles) intended for vaginal administration to achieve either local or systemic effect are reviewed. As for thermogelling systems, poly(ethylene oxide-propylene oxide-ethylene oxide) copolymer-based and chitosan-based formulations are discussed as thermogelling systems. The methods employed for functional characterization of both mucoadhesive and thermogelling drug delivery systems are also briefly described.

Co-delivery of a hydrophobic small molecule and a hydrophilic peptide by porous silicon nanoparticles.

Nanoparticulate drug delivery systems offer remarkable opportunities for clinical treatment. However, there are several challenges when they are employed to deliver multiple cargos/payloads, particularly concerning the synchronous delivery of small molecular weight drugs and relatively larger peptides. Since porous silicon (PSi) nanoparticles (NPs) can easily contain high payloads of drugs with various properties, we evaluated their carrier potential in multi-drug delivery for co-loading of the hydrophobic drug indomethacin and the hydrophilic human peptide YY3-36 (PYY3-36). Sequential loading of these two drugs into the PSi NPs enhanced the drug release rate of each drug and also their amount permeated across Caco-2 and Caco-2/HT29 cell monolayers. Regardless of the loading approach used, dual or single, the drug permeation profiles were in good correlation with their drug release behaviour. Furthermore, the permeation studies indicated the critical role of the mucus intestinal layer and the paracellular resistance in the permeation of the therapeutic compounds across the intestinal wall. Loading with PYY3-36 also greatly improved the cytocompatibility of the PSi NPs. Conformational analysis indicated that the PYY3-36 could still display biological activity after release from the PSi NPs and permeation across the intestinal cell monolayers. These results are the first demonstration of the promising potential of PSi NPs for simultaneous multi-drug delivery of both hydrophobic and hydrophilic compounds.

Evaluation of the physicochemical and biopharmaceutical properties of fluoro-indomethacin.

Drug nanocarriers have shown great potential in therapy and as diagnostic probes, e.g. in imaging of cancer and inflammation. Imaging can be applied to localize the carrier or the drug itself in the body and/or tissues. In this particular case it is important that drug molecules have the characteristics for possible detection, e.g. after modification with positron emission tomography compliant radioisotopes, without affecting their pharmacological behavior. In order to easily and efficiently follow the ADME profile of the drug after loaded into nanocarriers, the drug can be radiolabelled with, e.g. 18F-label, in order to assess its biodistribution after enteral and parenteral administration in rats. However, this is only possible if the derivative compound behaves similarly to the parent drug compound. In this study, indomethacin (a poorly water-soluble drug) was chosen as a model compound and aimed to evaluate the physicochemical and biopharmaceutical properties of an analog of indomethacin (IMC), fluoro-indomethacin (F-IMC). Although some of the physicochemical and biopharmaceutical properties of IMC are already known, in order to establish a feasible comparison between IMC and F-IMC, the behavior of the former was also investigated in the same conditions as for F-IMC. In this context, both IMC and F-IMC were thermally and morphologically studied. Furthermore, the following properties were also studied for both compounds: pKa and logP, solubility and dissolution profiles at physiological pH values, and toxicity at different concentrations in Caco-2 cells. Finally, the transport across Caco- 2 monolayers of the IMC and F-IMC at physiological pH range was also investigated. The results obtained showed similar values in pKalogP, solubility, dissolution, cytotoxicity, and permeability for both compounds. Thus, there might be strong evidence that both IMC and F-IMC should have a similar ADME behavior and profiles in vivo. The results provide fundamental tools and ideas for further research with nanocarriers of 18F-IMC.

New therapeutic platforms for the treatment of epithelial and cutaneous lesions.

There are still so-called unmet needs in the treatment of epithelial and cutaneous lesions. Mucositis, ocular lesions, chronic skin wounds represent typical examples. These pathologies do not yet afford a satisfactory treatment. In particular chronic wounds represent a major health care burden, likely to increase as the population ages. Healing of epithelial and cutaneous lesions progresses through a complex cascade of events starting with the secretion in the local environment of a pool of growth factors, cytokines and proteins from the serum and degranulating platelets. Recently platelet lysate (PL), a hemoderivative obtained by platelet destruction by freeze-thawing of a platelet rich plasma (PRP) sample in the presence of an anticoagulant agent, has proved capable of promoting the healing of buccal and corneal lesions. Since the efficacy of growth factors (GFs) critically depends on the way they are made available to the injured tissue, the development of suitable therapeutic vehicles is of paramount importance to release GFs according to the repairing requirements. The present work focuses on the development and testing of few such formulations, in particular a mucoadhesive gel and an in situ gelling buccal spray for the treatment of oral mucositis, and a thermosensitive eye drop solution for corneal lesions. Besides technological characterization, the formulations have been preliminarily screened with an ELISA assay, a cell proliferation test and an in vitro wound healing test. Some formulations have been used in early clinical trials.

Mucoadhesive behaviour of emulsions containing polymeric emulsifier.

Over the last two decades the attention has been focused on mucoadhesive dosage forms as a possibility to improve the residence time on a specified region of the body. In addition to bioadhesivity, controlled drug release from the dosage form is also desirable. Pemulen TR1 and Pemulen TR2 are cross-linked block copolymers of poly(acrylic acid) and hydrophobic long-chain methacrylates. They are able to stabilize o/w emulsions because their short lipophilic part integrates into the oil droplets whilst their long hydrophilic part forms a micro-gel around the droplet. In this study, correlations between the microstructure of these emulsions and the bioadhesive behaviour were found. Rheological and thermogravimetric methods were used to examine the microstructure of the emulsions. The mucoadhesive measurements were performed by tensile test and the bioadhesive bond between the polymer emulsifier and mucin was visualized by confocal laser scanning microscopy. It was established that (i) these emulsion form a special structure, which depends on the components, (ii) there were no remarkable changes in bioadhesive force and work when the oil content was increased in the emulsions, and (iii) the emulsions in which the polymeric emulsifier formed a special structure showed stronger adhesivity than the ones with simple polymer network.

Buccal drug delivery: A challenge already won?

The main obstacles that drugs meet when administered via the buccal route derive from the limited absorption area and the barrier properties of the mucosa. The effective physiological removal mechanisms of the oral cavity that take the formulation away from the absorption site are the other obstacles that have to be considered. The strategies studied to overcome such obstacles include the employment of new materials that, possibly, combine mucoadhesive, enzyme inhibitory and penetration enhancer properties and the design of innovative drug delivery systems which, besides improving patient compliance, favor a more intimate contact of the drug with the absorption mucosa.:

Characteristics of hydroxypropyl methylcellulose influencing compactibility and prediction of particle and tablet properties by infrared spectroscopy.

Particle characteristics, chemical substitution, compaction behavior, and tablet properties of hydroxypropyl methylcellulose powders from two different suppliers were related using multivariate data analysis. By Principal Component Analysis it was shown that the the degree of substitution of the HPMC powders did not correlate to the particle and compaction properties as strongly as anticipated. Particle shape and powder surface area seem to be more important for the compaction behaviour of the powders than the degree of substitution. In addition, particle and tablet properties were predicted from infrared spectral data. Fourier transform infrared (FTIR) and near infrared (NIR) spectral data of the powders were combined with measured values of the particle characteristics, compaction behavior, and tablet properties using the multivariate data analysis program SIMCA 7.1. Properties like density, particle shape, tablet tensile strength, and drug release characteristics of the HPMC powders and corresponding tablets in this study could be predicted using Partial Least Squares models. In conclusion, the particle shape and powder surface area of HPMC powders seem to be important factors for the quality of tablet attained. Further, this study confirms that NIR and FTIR analysis used in combination with multivariate analysis are powerful tools for predicting the properties of materials and the quality of the end product.